Biology subjects

Tang, S.-J.

Publications and source records attributed to Tang, S.-J..

10 recordsLinked to original sources

bioRxiv2025

Development of noninvasive imaging to measure spontaneous pain in mice

Objectively measuring pain in laboratory animals is essential for pain research and analgesic development. Despite the development of various behavioral tests to measure evoked pain in animal models, measuring spontaneous pain remains challenging. To address this unmet need, we developed a novel imaging approach to detect spontaneous nociception in animal pain models. To do this, we generated a Bacterial Artificial Chromosomes transgenic mouse that expresses Redquorin under the murine synapsin 1 promoter. Redquorin is a fusion protein consisting of chimera and a 2x tandem dimer Tomato Aequorin (tdTA), which emits long wavelength bioluminescence from activated neurons in the presence of coelenterazine. This luminescence can penetrate tissues and form a projected image on the body surface that can be detected with a spectrum In Vivo Imaging System, thus creating a Nociceptive Neuronal Activity Imaging mouse. We used the tdTA mice to image bioluminescence in the spinal regions as a surrogate of spontaneous pain induced by capsaicin, the HIV-1 envelope glycoprotein gp120, and spinal nerve ligation. Results show that Redquorin-emitted bioluminescence is a sensitive optical surrogate to measure spontaneous pain. This approach offers a new method to measure spontaneous pain in animal models for basic and translational research.

neuroscience↗

bioRxiv2022

A novel subtype of reactive astrocytes critical for HIV associated pain pathogenesis

Pathological pain is common in HIV patients, but the underlying mechanism remains elusive and therapeutic targets for effective treatment have not been identified. Reactive astrocytes are specifically activated in the spinal dorsal horn (SDH) of HIV patients with pathological pain and required for the development of HIV-associated pain in mouse models. These findings suggest a key role of reactive astrocytes in HIV-associated pain pathogenesis. However, due to the heterogeneity of reactive astrocytes, the pathogenic subtype is unknown. Using single-nucleus RNA-seq (snRNA-seq) transcriptomic analysis, we identified a novel subtype of HIV-pain associated astrocytes (HIPAs) in the lumbar spinal cord of the HIV -1 gp120 transgenic model. HIPAs were galectin 3 (Gal3)-positive and had transcriptomic signatures of phagocytosis and inflammation; they were also induced in the spinal cord of HIV patients. We showed HIPAs phagocytosed neuronal and synaptic components and were associated with neuronal degeneration. We found that knockout (KO) of Gal3 in gp120 transgenic mice severely diminished HIPAs. Interestingly, the activation of other astrocytes (e.g., homeostatic astrocytes) were also diminished in the Gla3 KO/gp120 transgenic mice. These results indicate that Gal3 is critical for gp120 to induce HIPAs, and that Gal3 may directly or via HIPAs to control the activation of other subtypes of astrocytes. Finally, we showed that the loss of HIPAs caused by Gal3 KO was associated with attenuated neuronal degeneration, neuroinflammation, and pain in gp120 transgenic mice. Collectively, our data suggest that HIPAs are a Gal3-expressing astrocytic subtype that mediates gp120-induced neurodegeneration and neuroinflammation in the spinal pain neural circuit during pain pathogenesis and is a potential cell target for treating HIV-associated pain.

neuroscience↗

bioRxiv2022

Nucleoside reverse transcriptase inhibitors are the major class of HIV antiretroviral therapeutics that induce neuropathic pain in Mice

AO_SCPLOWBSTRACTC_SCPLOWThe development of combination antiretroviral therapy (cART) has transformed human immunodeficiency virus (HIV) infection from a lethal diagnosis into a chronic disease, and people living with HIV on cART can experience an almost normal life expectancy. However, these individuals often develop various complications that lead to decreased quality of life, one of the most significant of which is neuropathic pain and development of painful peripheral sensory neuropathy (PSN). Critically, although cART is thought to induce pain pathogenesis, the relative contribution of different classes of antiretrovirals has not been systematically investigated. In this study, we measured development of pathological pain and peripheral neuropathy in mice orally treated with distinct antiretrovirals at their translational dosages. Our results show that only nucleoside reverse transcriptases (NRTIs), but not other types of antiretrovirals, such as proteinase inhibitors, non-nucleoside reverse transcriptase inhibitors, integrase strand transfer inhibitors, and CCR5 antagonists, induce pathological pain and PSN. Thus, these findings suggest that NRTIs are the major class of antiretrovirals in cART that promote development of neuropathic pain. As NRTIs form the essential backbone of multiple different current cART regimens, it is of paramount clinical importance to better understand the underlying mechanism to facilitate design of less toxic forms of these drugs and or potential mitigation strategies.

neuroscience↗

bioRxiv2021

Development of opioid-induced hyperalgesia depends on reactive astrocytes controlled by Wnt5a signaling

Opioids are the frontline analgesics for managing various types of pain. Paradoxically, repeated use of opioid analgesics may cause an exacerbated pain state known as opioid-induced hyperalgesia (OIH), which significantly contributes to dose escalation and consequently opioid overdose. Neuronal malplasticity in pain circuits has been the predominant proposed mechanism of OIH expression. Although glial cells are known to become reactive in OIH animal models, their biological contribution to OIH remains to be defined and their activation mechanism remains to be elucidated. Here, we show that reactive astrocytes (a.k.a. astrogliosis) are critical for OIH development in both male and female mice. Genetic ablation of astrogliosis inhibited the expression of OIH and morphine-induced neural circuit polarization (NCP) in the spinal dorsal horn (SDH). We found that Wnt5a is a neuron-to-astrocyte signal that is required for morphine-induced astrogliosis. Conditional knock-out of Wnt5a in neurons or its co-receptor ROR2 in astrocytes blocked not only morphine-induced astrogliosis but also OIH and NCP. Furthermore, we showed that the Wnt5a-ROR2 signaling-dependent astrogliosis contributes to OIH via inflammasome-regulated IL-1{beta}. Our results reveal an important role of morphine-induced astrogliosis in OIH pathogenesis and elucidate a neuron-to-astrocyte intercellular Wnt signaling pathway that controls the astrogliosis.

neuroscience↗

bioRxiv2021

Mechanism and role of astrogliosis in the pathogenesis of HIV-associated pain

Pathological pain is the most common neurological disorder in people living with HIV-1/AIDS (PLWHA), and rationale-based effective treatment is not available. Multiple neuropathologies develop in the pain transmission pathways in of HIV patients, consistent with their nociceptive dysfunction1,2. One of the prominent neuropathologies associating with the manifestation of pain in HIV patients is astrogliosis (a.k.a. reactive astrocytes) in the spinal dorsal horn (SDH)1, the spinal center for the transmission of pain signals from peripheral organs to the brain. However, the pathogenic role and the activation mechanism of astrogliosis are unclear. Here, we show that the astrogliosis is crucial for the pain pathogenesis induced by HIV-1 gp120, a key etiologically relevant protein2, and that a neuron-to-astrocyte Wnt5a signal controls the astrogliosis. We found that ablation of astrogliosis blocked the development of gp120-induced mechanical hyperalgesia, and concomitantly the expression of neural circuit polarization (NCP) in the SDH. In addition, we demonstrated that conditional knockout (CKO) of either Wnt5a in neurons or its receptor ROR2 in astrocytes abolished not only gp120-induced astrogliosis but also the hyperalgesia and the NCP. Furthermore, we found that the astrogliosis promoted expression of the NCP and the hyperalgesia via IL-1{beta} regulated by a Wnt5a-ROR2-MMP2 axis. Our results elucidate an important role and a novel mechanism of astrogliosis in the pathogenesis of HIV-associated pain. Targeting reactive astrocytes by manipulating the mechanistic processes identified here may lead to the development of effective therapy to treat the pain syndrome in HIV patients.

neuroscience↗

bioRxiv2021

Microglial ablation does not affect opioid-induced hyperalgesia in rodents

Opioids are the frontline analgesics in pain management. However, chronic use of opioid analgesics causes paradoxical pain that contributes to the decrease of their efficacy in pain control and the escalation of dose in long-term management of pain. The underling pathogenic mechanism is not well understood. Microglia have been commonly thought to play a critical role in the expression of opioid-induced hyperalgesia (OIH) in animal models. We performed microglial ablation experiments using either a genetic (CD11b-diphtheria toxin receptor transgenic mouse) or pharmacological (colony-stimulating factor 1 receptor inhibitor PLX5622) approaches. Surprisingly, ablating microglia using these specific and effective approaches did not cause detectable impairment in the expression of hyperalgesia induced by morphine. We confirmed this conclusion with behavioral test of mechanical and thermal hyperalgesia, in male and female mice, and with different species (mouse and rat). These findings raise caution about the widely assumed contribution of microglia to the development of OIH.

neuroscience↗

bioRxiv2020

Drosophila model of Anti-retroviral therapy Induced Peripheral Neuropathy and Nociceptive Hypersensitivity

The success of antiretroviral therapy (ART) has improved the survival of HIV-infected patients significantly. However, significant numbers of patients on ART whose HIV disease is well controlled show peripheral sensory neuropathy (PSN), suggesting that ART may cause PSN. Although the nucleoside reverse transcriptase inhibitors (NRTIs), one of the vital components of ART, are thought to contribute to PSN, the mechanisms underlying the PSN induced by NRTIs are unclear. In this study, we developed a Drosophila model of NRTI-induced PSN that recapitulates the salient features observed in patients undergoing ART: PSN and nociceptive hypersensitivity. Furthermore, our data demonstrate that pathways known to suppress PSN induced by chemotherapeutic drugs are ineffective in suppressing the PSN or nociception induced by NRTIs. Instead, we found that increased dynamics of a peripheral sensory neuron may underlie NRTI-induced PSN and nociception. Our model provides a solid platform in which to investigate further mechanisms of ART-induced PSN and nociceptive hypersensitivity.

neuroscience↗

bioRxiv2020

Single cell RNA-seq analysis reveals compartment-specific heterogeneity and plasticity of microglia

Microglia are heterogeneous and ubiquitous CNS-resident macrophages that maintain homeostasis of neural tissues and protect them from pathogen attacks. Yet, their differentiation in different compartments remains elusive. We performed single cell RNA-seq (scRNA-seq) analysis to compare the transcriptomes of microglia in adult mouse (C57/Bl) brains and spinal cords to identify microglial subtypes in these CNS compartments. Cortical microglia from 2-month mice consisted of a predominant population of the homeostatic subtype (HOM-M) and a small population (4%) of the inflammatory subtype (IFLAM-M), while spinal microglia consisted of 55% HOM-M and 45% IFLAM-M subtype. Comparison of cortical and spinal microglia at 2, 4 and 8 months revealed consistently a higher composition of the IFLAM-M subtype in the spinal cord. At 8-month, cortical microglia differentiated a small new subtype with interferon response phenotypes (INF-M), while spinal microglia polarized toward a proinflammatory phenotype, as indicated by the increase of microglia expressing IL-1{beta}. To further characterize the differential plasticity of cortical and spinal microglial heterogeneity, we determined the microglial transcriptomes from HIV-1 gp 120 transgenic (Tg) mice, a model of HIV-associated neurological disorders. Compared with wild-type (Wt) cortical microglia, the gp120Tg cortical microglia had three new subtypes, with signatures of interferon I response (INF-M), cell proliferation (PLF-M), and myelination or demyelination (MYE-M) respectively; while INF-M and PLF-M subtypes presented at all ages, the MYE-M only at 4-month. In contrast, only the INF-M subtype was observed in the spinal microglia from 2- and 4-month gp120tg mice. Bioinformatic analysis of regulated molecular pathways of individual microglial subtypes indicated that gp120 more severely impaired the biological function of microglia in cortices than in the spinal cord. The results collectively reveal differential heterogeneity and plasticity of cortical and spinal microglia, and suggest functional differentiation of microglia in different CNS compartments.

neuroscience↗

bioRxiv2018

Mitochondrial genome annotation and phylogenetic placement of Oreochromis andersonii and O. macrochir among the cichlids of southern Africa

Genetic characterization of southern African cichlids has not received much attention. Here, we describe the mitogenome sequences and phylogenetic positioning of Oreochromis andersonii and O. macrochir among the cichlids of southern Africa. The complete mitochondrial DNA sequences were determined for O. andersonii and O. macrochir, two important aquaculture and fisheries species endemic to southern Africa. The complete mitogenome sequence lengths were 16642 bp and 16644 bp for O. andersonii and O. macrochir respectively. The general structural organization follows that of other teleost species with 13 protein-coding genes, 2 rRNAs, 22 tRNAs and a non-coding control region. Phylogenetic placement of the two species among other African cichlids was performed using Maximum Likelihood (ML) and Bayesian Markov-Chain-Monte-Carlo (MCMC). The consensus trees confirmed the relative positions of the two cichlid species with O. andersonii being very closely related to O. mossambicus and O. macrochir showing a close relation to both species. Among the 13 mitochondrial DNA protein coding genes ND6 may have evolved more rapidly and COIII was the most conserved. There are signs that ND6 may have been subjected to positive selection in order for these cichlid lineages to diversity and adapt to new environments. More work is needed to characterize the southern Africa cichlids as they are important species for capture fisheries, aquaculture development and understanding biogeographic history of African cichlids. Bioconservation of some endangered cichlids is also essential due to the threat by invasive species.

genomics↗

bioRxiv2017

Exchange protein directly activated by cAMP plays a critical role in regulation of vascular fibrinolysis

RationaleTo maintain vascular patency, endothelial cells (ECs) actively regulate hemostasis. Among the myriad of pathways by which they control both fibrin formation and fibrinolysis is EC expression of annexin A2 (ANXA2) in a heterotetrameric complex with S100A10 [(ANXA2-S100A10)2]. This complex is a well-recognized endothelial surface platform for the activation of plasminogen by tissue plasminogen activator. A noteworthy advance in this field came about when it was shown that the cAMP pathway is linked to the regulation of (ANXA2-S100A10)2 in ECs.\n\nObjectiveThese findings prompted us to determine whether a druggable target, namely the exchange protein directly activated by cAMP (EPAC) pathway, plays a role in vascular luminal fibrinolysis.\n\nMethods and ResultsTaking advantage of our Epac1-null mouse model, we found that depletion of Epac1 results in fibrin deposition, fibrinolytic dysfunction, and decreased endothelial surface ANXA2 in mice, which are similar to phenomena discovered in ANXA2-null and S100A10-null mice. We observed upregulation of EPAC1 and downregulation of fibrin in endocardial tissues beneath atrial mural thrombi in humans. Of note, our thrombosis model revealed that dysfunction of fibrinolysis in EPAC1-null mice can be ameliorated by recombinant ANXA2. Furthermore, we demonstrated that suppression of EPAC1 using a small-molecule inhibitor (ESI09) reduces the expression of ANXA2 in lipid rafts and impedes ANXA2 association with S100A10. Endothelial apical surface expression of both ANXA2 and S100A10 were markedly decreased in ESI09-treated ECs, which was corroborated by results from a nanoforce spectroscopy study. Moreover, inactivation of EPAC1 decreases tyrosine 23 phosphorylation of ANXA2 in the cell membrane compartment.\n\nConclusionsOur data reveal a novel role for EPAC1 in vascular fibrinolysis, by showing that EPAC1 is responsible for the translocation of ANXA2 to the EC surface. This process promotes conversion of plasminogen to plasmin, thereby enhancing local fibrinolytic activity.

cell biology↗